linux-kernel - [PATCH] IB/hfi1: replace deprecated strncpy

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Message-ID: <20230921-strncpy-drivers-infiniband-hw-hfi1-chip-c-v1-1-37afcf4964d9@google.com>
Date:   Thu, 21 Sep 2023 07:17:47 +0000
From:   Justin Stitt <justinstitt@...gle.com>
To:     Dennis Dalessandro <dennis.dalessandro@...nelisnetworks.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Leon Romanovsky <leon@...nel.org>
Cc:     linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-hardening@...r.kernel.org,
        Justin Stitt <justinstitt@...gle.com>
Subject: [PATCH] IB/hfi1: replace deprecated strncpy

`strncpy` is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.

We see that `buf` is expected to be NUL-terminated based on it's use
within a trace event wherein `is_misc_err_name` and `is_various_name`
map to `is_name` through `is_table`:
| TRACE_EVENT(hfi1_interrupt,
| 	    TP_PROTO(struct hfi1_devdata *dd, const struct is_table *is_entry,
| 		     int src),
| 	    TP_ARGS(dd, is_entry, src),
| 	    TP_STRUCT__entry(DD_DEV_ENTRY(dd)
| 			     __array(char, buf, 64)
| 			     __field(int, src)
| 			     ),
| 	    TP_fast_assign(DD_DEV_ASSIGN(dd);
| 			   is_entry->is_name(__entry->buf, 64,
| 					     src - is_entry->start);
| 			   __entry->src = src;
| 			   ),
| 	    TP_printk("[%s] source: %s [%d]", __get_str(dev), __entry->buf,
| 		      __entry->src)
| );

Considering the above, a suitable replacement is `strscpy_pad` due to
the fact that it guarantees NUL-termination on the destination buffer
while maintaining the NUL-padding behavior that strncpy provides.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@...r.kernel.org
Signed-off-by: Justin Stitt <justinstitt@...gle.com>
---
Note: build-tested
---
 drivers/infiniband/hw/hfi1/chip.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/hw/hfi1/chip.c b/drivers/infiniband/hw/hfi1/chip.c
index 0814291a0412..7b8e1456284f 100644
--- a/drivers/infiniband/hw/hfi1/chip.c
+++ b/drivers/infiniband/hw/hfi1/chip.c
@@ -5334,7 +5334,7 @@ static const char * const cce_misc_names[] = {
 static char *is_misc_err_name(char *buf, size_t bsize, unsigned int source)
 {
 	if (source < ARRAY_SIZE(cce_misc_names))
-		strncpy(buf, cce_misc_names[source], bsize);
+		strscpy_pad(buf, cce_misc_names[source], bsize);
 	else
 		snprintf(buf, bsize, "Reserved%u",
 			 source + IS_GENERAL_ERR_START);
@@ -5374,7 +5374,7 @@ static const char * const various_names[] = {
 static char *is_various_name(char *buf, size_t bsize, unsigned int source)
 {
 	if (source < ARRAY_SIZE(various_names))
-		strncpy(buf, various_names[source], bsize);
+		strscpy_pad(buf, various_names[source], bsize);
 	else
 		snprintf(buf, bsize, "Reserved%u", source + IS_VARIOUS_START);
 	return buf;

---
base-commit: 2cf0f715623872823a72e451243bbf555d10d032
change-id: 20230921-strncpy-drivers-infiniband-hw-hfi1-chip-c-5b9ea605e6c4

Best regards,
--
Justin Stitt <justinstitt@...gle.com>